Manufacture of shoe stiffeners



Patented May I2, 1936 Y UNITED STATES PATENT OFFIC 2,040,320 Manor-norms or snon STIFFENERS Stanley P. Lovell, Newton, Mass., assignor, by

mesne assignments, to Beckwith Manufacturing Company, Dover, N. 11., a corporation of New Hampshire No Drawing. Application March 11, 1933, Serial'No. 660,136

6 Claims. (Cl. 36-77) This invention relates broadly to shoe stlfienskiving, whereas a shatterable binder may be rer ers made up of a fibrous foundationcarrying leased into the atmosphere in large quantity as therein as the impregnating or stiffening charge finely divided, inflammable dust. Again, I have various stiffening agents such as heretofore used found that certain binders which respond or disbut in combination with synthetic resins. The solve nicely in theorganic solvents of the stiffstiffening agents embraced by this invention are ener compound may yield in combination with preferably of the cellulose ester type soluble in the stiffening compound a mass which is so organic solvents and the synthetic resins are plastic .or fluent that it exudes under lasting preferably those prepared as chemical condensapressure or Wipin f m h Sh e ifl f ntion products from various starting chemicals dation in which it is initially carried to other 10 and preferably possessing such qualities as ability parts of the shoe upper- In ch c he Simto bond well both with the fibrous foundation and ener blank 's a so apt o b messy -t ense with the cellulose ester or other stiifening agent, that it is difiicult for the operator to handle it non-shatterability, andability to condense or and assemble it with the shoe upper without oxidize to a further degree after entering in comsmudging his fingers and the shoe upper, bination with the stiffening agent into the fibrous I have discov r d that w n fin y divided foundation. stiffening compound is mixed in an aqueous me- This invention relates more particularly to that dium with synthetic resins, the mixture then type of shoe stiffener in which finely divided or charged into a fib us foundation. nd he pulverulent colloidal stiffening compound is cara ed ou a dried, the resulting PrOdllOt ried as an, impregnating charge in a fibrous founis practically without any of the aforementioned dation, the stiifening compound being designed defects and is eminently serviceable for use in subsequently to be treated with, and be plasmaking box toe stifieners and other shoe stiffticized by, an organic solvent, so that the stiffn r Par s. Th t p 1' n h i r sin emener can be rendered limp and moldable by such Di y m y V y W hin W mi and f r solvent for assembly with a shoe upper and then mp i 7 conformed to the shape of the last during the (1) The so-celled vinyl resins p pa ed by compulling-over and bed-lasting operations to which illin vinyl a hol and an organic acid, as the assembled upper is subjected. typified by vinyl acetate;

It. is to be observed that a stiffening compound. (2) The resins made from polybasic acids, polyreduced to particles of small unit size will not be hy rie a hols, an if d ire modifyin n suitable for the foregoing purpose unless the paras typified by glycerol phthalate; ticles are bonded to the fibrous foundation and (3) h D f s. m r m p n to one another by some third element or comiv iv u h rubber; pound. Various attempts to manufacture the (4) The glyptal resins. desired article have been made. Thus, I am Whi ny f the ve ypes of resins may be aware of a process wherein rosin size and/or rubemployed, I prefer a phthalate resin, having seber latex have been specifically employed as the c red he best re ul s to dat by using a resin binding agent, but this expedient gives rise to produced as the reaction product of colophony certain difilculties, some of which will hereinafter and maleic acid and combined with tung oil and 40 be mentioned. tung fatty acids in the presence of certain me- I have made a very great number of experi- 'tallic salts or so-called driers. ments in an endeavor to compound or mix a As a specific example of my invention, I cite finely divided stifi'ening compound with a suitthe following formula for charging the fibrous able binder to form a composition which, upon foundation, whi h win he understood a typical drying or setting, will adequately hold or grip the and t limiting;

fibrous foundation and y'et'be sufliciently porous Parts to allow the influx of organic solvent into and P :hroughout the foundation with proper coalescing g ggz z fifii i i i f gg )r colloiding of the particles of stiffening com- Inert dispersion liquid 250 to iound. u

I have found that grave dimcult'ies may arise The stiffening compound used in the foregoing n skiving the edge portions of shoe stifi'eners s'o' formula may be any suita le n lu l r elatnade, since too plastic a 'binder will fuse and inizablein an organic solvent, but I prefer to boom gummy under the intense friction of use celllulose esters, such as celluloid, cellulose operatiims.

2 acetate, etc., or mixtures of the esters. The syn. thetic resin may be any one of those named, but I prefer to use one which progressively condenses or oxidizes in the foundation under atmospheric influences. The dispersion liquid or carrier for the mixture, making possible its introduction as an impregnant into and throughout the fibrous foundation, is preferably water. The mixture produced according to the formula is preferably passed through a colloid mill, homogenizer, or other dispersing machine; which delivers a smooth, substantially paste-like consistency. This paste is incorporated into the fibrous foundation, for instance, by passing canton flannel, felt, or other woven or felted fabric through calender or squeeze rolls in front of which a bank of the paste is maintained for forcing into and throughout the fabric in desired amount. Upon drying or evaporation of the liquid from the charged foundation, the powdered stiffening compound is found to be bonded par ticle to particle and particle to fiber by the binder, but, as already indicated the mixture of stiffening compound and binder exists in a porous state in the foundation. The dried fabric is then cut or dried out into box toe blanks or other shoe stiffeners, which can readily be skived without liberating dust and from which stiffening compound does not ooze to any material extent when conditioned with solvent for the'stiifening compound and put through customary shoe-making When my shoe stiffeners madeas hereinbefore described are subjected to organic solvents and incorporation into shoe uppers, the resultant qualities realized in the stiifeners are neither those of the stiffening compound alone nor of the'synthetic resin alone, but a combination of the desirable physical qualities of both. Thus, the hardness and shock-resistance of the condensation product or synthetic resin are realized together with the stiffness and resilience of the stiffening compound. Since further condensation or oxidation of the synthetic resin may' take place slowly and progressively, the desired end results may be realized only after the stiffener has remained for some time in the finished shoe, during which time-the condensation or oxidation proceeds to-an equilibrium.

. It might be observed that when the pulverulent stiffening compound is a cellulose ester, such as cellulose acetate and/ or cellulose nitrate, and the synthetic resin serving as the binder is a polyvinyl ester resin,-such as polyvinyl acetate, the shoe stiffener of the present invention comprising a porous fibrous foundation carrying as an impregnating charge a combination of the cellulose ester and the polyvinyl ester resin may be rendered limp and moldable by the' colloiding or gelatinizing action of an organic solvent on both of the components of theimpregnating-charge. Thus, there are some organic solvents that are solvents of both cellulose esters and polyvinyl ester resins so that when the shoe stiffener of the present invention is treated with such organic homogeneous mixture of solvents, not only do such solvents penetrate into and throughout the fibrous foundation of the stiffener, by reason of the porosity of the foundation and the porosity of the impregnating charge therein, but function to gelatinize both the cellulose ester and the polyvinyl ester to effect an intimate blending of the two esters and thus to develop in the set, molded stiffener in the shoe a combination of the desirable physical qualities of both.esters, as hereinbefore described.

I claim:--- 1 1. A shoe stiffener comprising a porous fibrous foundation containing incorporated therein a mixture of finely divided cellulose ester and a synthetic resin selected from a class consisting of the phthalate resins, the vinyl resins, the glyptal resins, and the plioform resins in bonded relationship to each other-and to the foundation, said mixture existing in a porous state in said foundation and permitting solvent of said ester to penetrate into and throughout said foundation with colloiding action on said ester.

2. A shoe stiifener comprising a porous fibrous zfoundation containing incorporated therein a mixture of finely divided cellulose ester and 'phthalate resin in bonded relationship to each other and to the foundation, said mixture existing in a porous state in said foundation and permitting solventof said ester to penetrate into and throughout said foundation with colloidlng action.

on said ester.

3. A shoe stiffener comprising a porous fibrous foundation containing incorporated therein a mixture of finely divided cellulose ester soluble in organic solvents and polymerized phthalate resin in bonded relationship to each other and to the foundation, said mixture existing in a pmous state in said foundation and permitting solvent of said cellulose ester to penetrate into and throughout said foundation with colloiding action on said cellulose ester.

4. A shoe stiifener comprising a porous fibrous foundation containing incorporated therein a mixture of a preponderant proportion of finely divided cellulose ester soluble in organic solvents and a subordinate proportion of polymerized phthalate resin in bonded relationship to each other and to the foundation, said mixture existing in a porous state in said foundation and permitting solvent of said cellulose ester to penetrate into and throughout said foundation with colloiding action on said cellulose ester.

5. A shoe stiffener comprising a porous fibrous foundation stiffened by a finely divided mixture of different agents, said agents including a cellulose ester soluble in an organic solvent and a vinyl ester resin' and being bonded to said foundation and to each other.

6. A shoe stiffener comprising a porous fibrous foundation stiffened by a finely divided mixture of different agents, said agents including a preponderant proportion of a cellulose ester soluble in an organic. solvent and a subordinate proportion of a vinyl ester resin and being bonded to said foundation and to each other.

STANLEY P.1OVE1L. 

